Theories

I have already written about the two physicists who did the most to talk me into taking many-worlds and the wider multiverse seriously, so when a new YouTube channel showed up in my feed built entirely around the premise that science doesn’t have to be baffling, I was always going to click. Unbaffled, presented by Professor Jim Al-Khalili, launched on 25 June 2026, and in its first three weeks it has already covered quantum interpretation, brain lateralisation, and whether time travel is physically permitted. That is a wide spread for a channel barely a month old, and it is exactly the range I wanted a profile to capture. ...

I already owed Sean Carroll a proper post. When I wrote A New Universe All Throughout The Day I admitted, almost in passing, that he was the person who really led me into taking the many-worlds interpretation seriously rather than treating it as a science-fiction gimmick. Then two New Scientist videos landed in front of me within a few weeks of each other - one titled We May Never Understand Reality and one titled Why Quantum Physics Says There’s a Multiverse - and I realised I had been circling him for months without ever writing the man down. This is me doing that. ...

I have written about one of Max Tegmark’s ideas already - the Mathematical Universe Hypothesis - and in doing so I admitted he sits at the top of my favourite physicists list. That post was about a single claim. This one is about the man, and about the thing I find more interesting than any individual theory of his: the through-line. Tegmark has spent a career moving steadily inward, from measurable cosmology toward the deepest possible questions about what reality is, and the move never feels like a physicist losing the plot and drifting into metaphysics. It feels like someone following the maths until it runs out of floor. ...

In Why Is There Something Rather Than Nothing? I admitted to an instinct I have never quite been able to shake: that the laws of physics are discovered rather than invented, and that mathematics might be genuinely fundamental - not a human language we lay over reality, but part of the bedrock. I said that if we ever reach base reality, maths is the thing most likely to get us there. I left it as a feeling. This post is me taking that feeling and seeing how far a serious physicist has been willing to push it. ...

“Are we living in a simulation?” is one of those questions that sounds like late-night dorm-room talk and then turns out to have a serious literature behind it. The honest short answer to “how likely” is that nobody knows, and that the question may not even have a clean numerical answer. But that is not a reason to wave it away. The reasons we cannot confidently put a number on it are themselves interesting, and they tell us something real about the limits of probability, the nature of consciousness, and what counts as science. ...

I have always had this strange gut feeling that the universe is, in some sense, new all throughout the day. Not new in the dramatic science-fiction sense, where everything resets and starts over, but new in the sense that reality seems to keep unfolding into fresh versions of itself depending on what happens next. A conversation goes one way instead of another. You decide to go out, or stay in. You send the message, or you leave it unsent. Tiny differences, and suddenly the entire shape of the day changes. ...

TL;DR The deepest question in cosmology: why is there something rather than nothing? - physics explains how the universe behaves once it exists, not necessarily why it exists at all Physicists’ “nothing” is not absolute absence - quantum vacua still have fields, rules, and structure Elegant physical laws and mathematics may be discovered rather than invented - part of why anything could exist Consciousness may be fundamental or emergent; either answer changes what a complete explanation would require I am a fascinated amateur, not a physicist - treat this as thinking out loud, not a verdict One of the strangest facts about reality is that there is any reality at all. ...

What Are Very Large Numbers? Large numbers exist on a spectrum so extreme that human intuition breaks down. From the observable universe containing roughly 10^80 atoms, to numbers so impossibly vast that they dwarf the atoms themselves, these magnitudes challenge our ability to comprehend scale. But they’re not just abstract curiosities. Large numbers appear in computer science (combinatorics, compression), physics (entropy, quantum possibilities), and mathematics (set theory, ordinal numbers). Understanding them requires leaving behind our everyday sense of “big” and embracing the mathematical structures that define these hierarchies. ...

Max Tegmark Cosmologist and physicist known for his work on the mathematical universe hypothesis and multiverse theory. His research bridges the gap between quantum mechanics and cosmology, exploring the deepest questions about the nature of reality. The Case for Halting AI Development Max Tegmark joins Lex Fridman to discuss the urgent need to pause advanced AI development, exploring the existential risks of artificial intelligence and what safeguards humanity needs as we approach transformative technologies. ...